1. Field of the Invention
This invention relates to a device for sensing damage to a tooth on a cogged belt, such as a timing belt.
2. Description of the Prior Art
In automotive diesel engines, a combination of a synchronous belt and pulleys is customarily used to couple the engine crankshaft to the engine camshaft and the drive shaft of a fuel injection pump. The belt has evenly spaced teeth on its inner surface which mesh with grooves on the pulleys to produce a positive, no-slip driving effect. Such belts are commonly called timing belts.
Timing belts are generally made of rubber, thus reducing noise and avoiding the need for a lubricating bath or oiling system which would be necessary in the case of chains or gears. Since the material of the belts is rubber, the service life of such belts is shorter than that of the main bodies of the engines. In final stages thereof, individual teeth break off the belt, which can result in slippage between the belts and the pulleys and thus disruption of fuel injection timing and opening and closing timing of the inlet and outlet valves in the engine cylinders.
In order to prevent such slippage, such belts are commonly visually inspected periodically, or are replaced periodically even if there is no damage to the belts.